In an X-ray CT apparatus, projection data of many two-dimensional images are acquired by rapidly rotating an X-ray source and an X-ray detector around an object (patient) while moving a table with the object loaded thereon in the rotation axis direction. Then, a three-dimensional image of the object is obtained by reconstructing the acquired many projection data.
In an X-ray CT apparatus, a rotating body, which houses various types of units such as a high voltage power source and a DAS (Data Acquisition System) aside from an X-ray source and an X-ray detector, rotates around an object at high speed. If the rotating body vibrates due to the rotational motion, or if the rotational motion becomes imbalanced, image quality deteriorates because the position of the X-ray detector fluctuates.
In order to reduce such vibration of the rotating body and imbalance of the rotational motion, technology to enhance strength and rigidity of a gantry supporting the rotating body has been considered.
Meanwhile, a weight for adjusting balance of the rotating body (i.e. eliminating imbalance of the rotating body) is disposed inside the rotating body, in addition to the aforementioned respective units. In the conventional balance adjustment method, imbalance is eliminated by adjusting heaviness of the weight and the position of the weight after assembling the gantry.
In the conventional balance adjustment method, firstly, measurement equipment for measuring fluctuation in rotation is attached by user operation, and then the heaviness of the weight and the position of the weight are adjusted on the basis of the measurement result by user operation as well. In order to appropriately determine the heaviness of the weight and the position of the weight, highly advanced skills are required for an operator.
In addition, balance adjustment is also required in the case of replacing a unit in the rotating body due to malfunction or the like, and thus, attaching and detaching of the measurement equipment, as well as adjusting the heaviness of the weight and the position of the weight are required each time of replacement.
Accordingly, an X-ray CT apparatus which can accurately adjust rotational balance in a short time without relying on skills of an operator has been desired.